/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.streaming.runtime.translators;

import org.apache.flink.api.common.ExecutionConfig;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.api.dag.Transformation;
import org.apache.flink.api.java.functions.KeySelector;
import org.apache.flink.streaming.api.graph.SimpleTransformationTranslator;
import org.apache.flink.streaming.api.graph.StreamGraph;
import org.apache.flink.streaming.api.operators.StreamOperatorFactory;

import javax.annotation.Nullable;

import java.util.Collection;
import java.util.Collections;
import java.util.List;

import static org.apache.flink.util.Preconditions.checkNotNull;
import static org.apache.flink.util.Preconditions.checkState;

/**
 * A utility base class for one input {@link Transformation transformations} that provides a
 * function for configuring common graph properties.
 */
abstract class AbstractOneInputTransformationTranslator<IN, OUT, OP extends Transformation<OUT>>
		extends SimpleTransformationTranslator<OUT, OP> {

	protected Collection<Integer> translateInternal(
			final Transformation<OUT> transformation,
			final StreamOperatorFactory<OUT> operatorFactory,
			final TypeInformation<IN> inputType,
			@Nullable final KeySelector<IN, ?> stateKeySelector,
			@Nullable final TypeInformation<?> stateKeyType,
			final Context context) {
		checkNotNull(transformation);
		checkNotNull(operatorFactory);
		checkNotNull(inputType);
		checkNotNull(context);

		final StreamGraph streamGraph = context.getStreamGraph();
		final String slotSharingGroup = context.getSlotSharingGroup();
		final int transformationId = transformation.getId();
		final ExecutionConfig executionConfig = streamGraph.getExecutionConfig();

		streamGraph.addOperator(
			transformationId,
			slotSharingGroup,
			transformation.getCoLocationGroupKey(),
			operatorFactory,
			inputType,
			transformation.getOutputType(),
			transformation.getName());

		if (stateKeySelector != null) {
			TypeSerializer<?> keySerializer = stateKeyType.createSerializer(executionConfig);
			streamGraph.setOneInputStateKey(transformationId, stateKeySelector, keySerializer);
		}

		int parallelism = transformation.getParallelism() != ExecutionConfig.PARALLELISM_DEFAULT
			? transformation.getParallelism()
			: executionConfig.getParallelism();
		streamGraph.setParallelism(transformationId, parallelism);
		streamGraph.setMaxParallelism(transformationId, transformation.getMaxParallelism());

		final List<Transformation<?>> parentTransformations = transformation.getInputs();
		checkState(
			parentTransformations.size() == 1,
			"Expected exactly one input transformation but found " + parentTransformations.size());

		for (Integer inputId: context.getStreamNodeIds(parentTransformations.get(0))) {
			streamGraph.addEdge(inputId, transformationId, 0);
		}

		return Collections.singleton(transformationId);
	}
}
